Ventilation unit

ABSTRACT

The ventilation unit includes: an explosion-proof valve that permits gas to flow from the inside of a housing to the outside of the housing when internal pressure within the housing is higher than external pressure outside the housing by a value larger than or equal to a predetermined value, and is capable of returning to block the flow of the gas from the inside of the housing to the outside of the housing; and a ventilation membrane that permits gas to flow between the inside and the outside of the housing even when a pressure difference between the internal pressure and the external pressure is less than the predetermined value.

TECHNICAL FIELD

The present invention relates to a ventilation unit.

BACKGROUND ART

Conventionally, a technique that provides a function of a ventilationhole to an explosion-proof valve of a battery pack to eliminate the needto separately provide the ventilation hole including a ventilationmembrane has been suggested.

For example, an explosion-proof valve described in Patent Document 1includes: an explosion-proof valve case formed of a synthetic resin, andforming an annular ring shape; an O-ring sealing between theexplosion-proof valve case and a pack case; a circular sheet-likeventilation membrane attached to the case so as to close a centralopening of the explosion-proof valve case; and a circular plate-likeprotector formed of a synthetic resin, and overlapped and arrangedoutside the ventilation membrane. Notches as ventilation holes areprovided around the protector, and a small amount of air can go in andout via the ventilation membrane. When an internal pressure rapidlyrises at battery abnormality, the protector is folded, and locking bylocking projections is released to drop the protector, and therefore, alarge passage cross-sectional area is secured instantaneously to releasethe internal pressure.

CITATION LIST Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open Publication No.

2013-168293

SUMMARY OF INVENTION Technical Problem

For example, in a vehicle-mounted large battery pack, it is desirable touse a ventilation member (for example, a ventilation membrane) foreliminating a pressure difference between the inside and the outside ofa housing with temperature changes in normal operation, and to use anexplosion-proof valve for eliminating a pressure difference due topressure increase when abnormality occurs. This is because there is apossibility that the ventilation member eliminating the pressuredifference at the normal time cannot sufficiently release the pressurein the housing that is instantaneously increased when abnormalityoccurs. Considering man-hours for assembling these ventilation memberand explosion-proof valve to the housing, it is desirable that theventilation member and the explosion-proof valve are unitized.

On the other hand, from the standpoint of ensuring functions of theventilation member and the explosion-proof valve, it is desirable thatnormal operations of these components can be inspected before shipmentof the products.

An object of the present invention is to provide a ventilating unit thatcan realize elimination of a differential pressure in normal time andelimination of a differential pressure when abnormality occurs whileenabling to make an inspection before shipment.

Solution to Problem

Under such an object, the present invention provides a ventilation unit(1) including: a first ventilation body (10) that permits gas to flowfrom an inside of a housing (120) to an outside of the housing (120)when internal pressure, which is pressure inside the housing (120), ishigher than external pressure, which is pressure outside the housing(120), by a value not less than a predetermined value, and is capable ofreturning to block flow of the gas from the inside of the housing (120)to the outside of the housing (120); and a second ventilation body (40)that permits gas to flow between the inside of the housing (120) and theoutside of the housing (120) even when a pressure difference between theinternal pressure and the external pressure is less than thepredetermined value.

Here, a support member (30) that supports the first ventilation body(10) and the second ventilation body (40) may be further included.

Moreover, a holding member (70) that holds the support member (30) andis attached to the housing (120) may be further included.

Moreover, the second ventilation body (40) may prevent a liquid and asolid from penetrating into the inside of the housing (120) from theoutside of the housing (120).

Moreover, the present invention provides a ventilation unit (1)including: a first ventilation body (10) that closes a first flow path(R1) when a pressure difference between internal pressure, which ispressure inside a housing (120), and external pressure, which ispressure outside the housing (120), is a value less than a predeterminedvalue, and is elastically deformed to open the first flow path (R1) whenthe internal pressure is higher than the external pressure by a valuenot less than the predetermined value; and a second ventilation body(40) that is provided to a second flow path (R2) and permits gas to flowbetween the inside of the housing (120) and the outside of the housing(120) via the second flow path (R2) even when the pressure differencebetween the internal pressure and the external pressure is less than thepredetermined value.

Here, a support member (30) that supports the first ventilation body(10) and the second ventilation body (40) may be further included.

Moreover, a holding member (70) that holds the support member (30) andis attached to the housing (120) may be further included.

Moreover, the support member (30) may be attached to the holding member(70) by being inserted into the holding member (70), the secondventilation body (40) may be fastened to the support member (30), andthe first ventilation body (10) is sandwiched between the support member(30) and the holding member (70).

Moreover, the holding member (70) may include a butted portion (72),against which a jig (250) used in inserting the support member (30) intothe holding member (70) is butted, and a position of the support member(30) with respect to the holding member (70) may be determined byinserting the support member (30) into the holding member (70) until thejig (250) is butted against the butted portion (72).

Moreover, the first ventilation body (10) may close the first flow path(R1) by contacting the holding member (70), and may open the first flowpath (R1) by separating from the holding member (70).

Note that the above signs in this section are provided forexemplification in describing the present invention, and the presentinvention is not restricted by these signs.

Advantageous Effects of Invention

According to the present invention, it is possible to provide aventilating unit that can realize elimination of a differential pressurein normal time and elimination of a differential pressure whenabnormality occurs, while enabling to make an inspection beforeshipment.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a general configuration of a vehicle loadedwith a battery pack to which a ventilation unit related to a firstexemplary embodiment is applied;

FIG. 2 is a diagram showing a general configuration of the battery pack;

FIG. 3 is a perspective view showing the ventilation unit related to thefirst exemplary embodiment;

FIG. 4 is a perspective view of components constituting the ventilationunit related to the first exemplary embodiment;

FIG. 5 is a cross-sectional view of the ventilation unit related to thefirst exemplary embodiment;

FIG. 6 is a diagram showing a state in which an explosion-proof valverelated to the first exemplary embodiment opened a first flow path;

FIG. 7A is a diagram showing a state before an internal pressureadjusting component is inserted into a holding member;

FIG. 7B is a diagram showing a state after the internal pressureadjusting component is inserted into the holding member;

FIG. 8 is a diagram showing an example of a state after a function ofthe explosion-proof valve related to the first exemplary embodiment wasinspected;

FIG. 9 is a cross-sectional view of a ventilation unit related to asecond exemplary embodiment;

FIG. 10 is a diagram showing a state in which an explosion-proof valverelated to the second exemplary embodiment opened the first flow path;

FIG. 11 is a perspective view of components constituting a ventilationunit related to a third exemplary embodiment;

FIG. 12 is a cross-sectional view of the ventilation unit related to thethird exemplary embodiment;

FIG. 13 is a diagram showing a state in which an explosion-proof valverelated to the third exemplary embodiment opened the first flow path;and

FIG. 14 is a diagram showing an example of a state after a function ofthe explosion-proof valve related to the third exemplary embodiment wasinspected.

DESCRIPTION OF EMBODIMENTS

Hereinafter, exemplary embodiments according to the present inventionwill be described in detail with reference to attached drawings.

First Exemplary Embodiment

FIG. 1 is a diagram showing a general configuration of a vehicle 200loaded with a battery pack 100 to which a ventilation unit 1 related toa first exemplary embodiment is applied. FIG. 1 is a diagram viewing thevehicle 200 from the side.

FIG. 2 is a diagram showing a general configuration of the battery pack100.

The vehicle 200 includes: a motor unit 201 provided to a front portionof a vehicle body; and the battery pack 100 provided to a bottom portionof the vehicle body to supply the motor unit 201 with electric power.The vehicle 200 is an electric vehicle that drives front wheels with adrive force outputted from the motor unit 201.

The battery pack 100 includes: a battery 110; a controller (not shown)for controlling the battery 110; various kinds of sensors (not shown)for detecting the state of the battery 110; and a housing 120 thatcontains the battery 110 or the controller.

The battery pack 100 also includes a ventilation unit 1 that is attachedto the housing 120 to adjust a pressure difference between an internalpressure of the housing 120 and an external pressure of the housing 120.The ventilation unit 1 is attached to the housing 120 so that acenterline direction to be described later is horizontal with theground.

{Ventilation Unit 1}

FIG. 3 is a perspective view showing the ventilation unit 1 related tothe first exemplary embodiment. FIG. 4 is a perspective view ofcomponents constituting the ventilation unit 1 related to the firstexemplary embodiment. FIG. 5 is a cross-sectional view of theventilation unit 1 related to the first exemplary embodiment.Hereinafter, the upper side in each of FIGS. 3 to 5 is referred to as“upward,” and the lower side thereof is referred to as “downward.”

The ventilation unit 1 includes, as an example of a first ventilationbody, an explosion-proof valve 10 that permits gas to flow from theinside of the housing 120 to the outside of the housing 120 wheninternal pressure, which is the pressure inside the housing 120 ishigher than pressure outside the housing 120 (external pressure) by avalue not less than a predetermined value, and blocks the flow of thegas from the inside of the housing 120 to the outside of the housing 120when the internal pressure is not higher than the external pressure by avalue not less than the predetermined value.

Moreover, the ventilation unit 1 includes an internal pressure adjustingcomponent 20 that permits gas to flow between the inside of the housing120 and the outside of the housing 120 when the pressure differencebetween the internal pressure and the external pressure is less than thepredetermined value.

The ventilation unit 1 also includes: a holding member 70 that holds theinternal pressure adjusting component 20 and is attached to the housing120; and a sealing member 80 that is disposed between the holding member70 and the housing 120 to seal the holding member 70 and the housing120.

(Internal Pressure Adjusting Component 20)

The internal pressure adjusting component 20 includes a support body 30as an example of a support member, which is attached to the holdingmember 70 and on which a communicating hole 33 for communicating theinside of the housing 120 with the outside of the housing 120 is formed.

Moreover, the internal pressure adjusting component 20 includes aventilation membrane 40 as an example of a second ventilation body thatis attached to the support body 30 to cover the communicating hole 33 toprevent liquids and solids from penetrating into the inside of thehousing 120 from the outside of the housing 120 while permitting flow ofgases between the inside of the housing 120 and the outside of thehousing 120.

The internal pressure adjusting component 20 also includes a cover 50that protects the ventilation membrane 40 from direct contact withhigh-pressure water and so forth.

<<Support Body 30>>

The support body 30 includes a support portion 31 for supporting theventilation membrane 40 and an insertion portion 32 to be inserted intothe holding member 70. At the center portion of the support body 30, thecommunicating hole 33 configured by a through hole that penetratesthrough the support portion 31 and the insertion portion 32 is formed.

The support portion 31 is a disk-shaped portion at a center portion ofwhich the communicating hole 33 is formed. The outer diameter of thesupport portion 31 is larger than the outer diameter of the insertionportion 32. The support portion 31 includes, around the communicatinghole 33, an annular-shaped supportive protruding part 31 a thatprotrudes in a direction different from that of the insertion portion32.

On an outer circumferential portion in the support portion 31, threelinear parts 31 b are provided at regular intervals in thecircumferential direction. At a lower end portion of each of the linearparts 31 b, a concave part 31 c that is inwardly concaved is formed. Aninward protruding part 52 a of an extending portion 52, which will bedescribed later, of the cover 50 is fitted into the concave part 31 c,and thereby the support body 30 holds the cover 50.

The insertion portion 32 has a cylindrical shape having an outerdiameter substantially the same as a center portion through hole 71 b,which will be described later, formed in the holding member 70.

The insertion portion 32 includes, at a tip end portion thereof, whichis on the side of starting to be inserted into the holding member 70,six leg portions 32 a divided along the circumferential direction. Eachof three leg portions 32 a, of the six leg portions 32 a, has an outwardprotruding part 32 b that is protruded outwardly in the radial directionfrom the outer surface. The leg portions 32 a provided with the outwardprotruding parts 32 b and the leg portions 32 a not provided with theoutward protruding parts 32 b are alternately disposed in thecircumferential direction. The outward protruding parts 32 b of the legportions 32 a are positioned below the center portion through hole 71 bformed in the holding member 70 and are butted against a bottom portion71, which will be described later, of the holding member 70, and therebythe support body 30 is prevented from detaching from the holding member70.

As the material of the support body 30, though not particularly limited,a thermoplastic resin, which is easily molded, is preferred. As thethermoplastic resin, examples of thermoplastic resins except forelastomer can include polybutylene terephthalate (PBT), polyethyleneterephthalate (PET), polyphenylene sulfide (PPS), polysulfone (PS),polypropylene (PP), polyethylene (PE), ABS resin or a composite materialthereof. Moreover, the examples of the material of the support body 30can include a composite material made by combining a reinforcement, suchas glass fiber or carbon fiber, or metal with the thermoplastic resin toimprove heat resistance, humidity resistance, dimensional stability,rigidity or the like.

The molding method of the support body 30 is not particularly limited;examples thereof can include injection molding, compression molding orcutting.

<<Ventilation membrane 40>>

The ventilation membrane 40 is formed in a disk shape. The outerdiameter of the ventilation membrane 40 is larger than the outerdiameter of the supportive protruding part 31 a of the support portion31 in the support body 30. The ventilation membrane 40 is supported bythe supportive protruding part 31 a of the support portion 31 to coverthe communicating hole 33. Examples of the supporting method can includejoining by welding the ventilation membrane 40 to the supportiveprotruding part 31 a. Other than this, ventilation membrane 40 and thesupportive protruding part 31 a may be bonded by a bonding agent or adouble-faced tape. Moreover, the ventilation membrane 40 and the supportbody 30 may be integrated by insert molding. Alternatively, theventilation membrane 40 may be swaged to the support body 30.

The material, the structure and the form of the ventilation membrane 40are not particularly limited as long as a sufficient air permeableamount can be secured. Examples of the ventilation membrane 40 caninclude at least a kind selected from a fluorine resin porous body and apolyolefine porous body. As the fluorine resin, polytetrafluoroethylene(PTFE), polychlorotrifluoroethylene,tetrafluoroethylene-hexafluoropropylene copolymer,tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer,tetrafluoroethylene-ethylene copolymer and so forth can be taken asexamples. Examples of polyolefine monomers can include: ethylene;propylene; 4-methylpentene-1; and 1-butene, and polyolefine obtained byhomopolymerizing or copolymerizing these monomers can be used. Moreover,the material may be obtained by blending at least two kinds ofpolyolefine, or may be a layer structure of at least two kinds ofpolyolefine. Of these, it is particularly preferable that theventilation membrane 40 is made of a PTFE porous body that is able tomaintain a ventilating property even with a small area and is highlyfunctional to prevent entry of water or dust into the inside of thehousing 120.

Note that a reinforcing material may be laminated to form a layer on atleast one surface of the ventilation membrane 40. The material, thestructure and the form of the reinforcing material are not particularlylimited; however, a material having pore diameters larger than those ofthe ventilation membrane 40 and good ventilating properties, such as awoven cloth, a non-woven cloth, a mesh, a net, a sponge, a foam, a metalporous body or a metal mesh is suitable. When heat resistance isrequired, the reinforcing material made of polyester, polyamide, aramidresin, polyimide, fluoride resin, ultrahigh molecular weightpolyethylene, metal or the like is preferred.

«Cover 50»

The cover 50 includes a disk-shaped top portion 51 and the extendingportions 52 extending from an outermost circumferential part in the topportion 51 toward the support body 30.

The outer diameter of the top portion 51 is larger than the outerdiameter of the ventilation membrane 40, and the top portion 51 coversthe ventilation membrane 40 at a position via a predetermined intervalfrom the ventilation membrane 40.

The extending portions 52 are formed at three locations at regularintervals in the circumferential direction. The extending portion 52includes, at the end portion thereof on the support body 30 side, theinward protruding part 52 a that protrudes inwardly. The inwardprotruding parts 52 a are fitted into the concave parts 31 c formed inthe support portion 31 of the support body 30, and thereby the cover 50is held by the support body 30. Gaps between the extending portions 52function as a part of the flow path of gases communicating between theinside of the housing 120 and the outside of the housing 120.

The cover 50 is made of the same material as the support body 30, forexample.

Note that the method of integrating the cover 50 and the support body 30is not limited to the above-described method that fits the inwardprotruding parts 52 a of the cover 50 into the concave parts 31 c formedin the support body 30. For example, the cover 50 and the support body30 may be integrated by thermal welding, ultrasonic welding, oscillatorywelding, bonding using a bonding agent, threading or the like.

By covering the ventilation membrane 40 with the cover 50, theventilation membrane 40 is prevented from being damaged by externalforces, or ventilation is prevented from being blocked due to sand, mudand so forth piled on the surface of the ventilation membrane 40.

(Holding Member 70)

The holding member 70 includes: a disk-shaped bottom portion 71; a sideportion 72 that protrudes upwardly in the centerline direction from theoutermost circumferential part in the bottom portion 71 to be providedin the side direction of the ventilation membrane 40 of the internalpressure adjusting component 20 or the cover 50; and an attachingportion 73 that protrudes downwardly in the centerline direction fromthe outer circumferential part in the bottom portion 71 to be attachedto the housing 120.

The bottom portion 71 includes, at the center portion thereof, a centralprotruding part 71 a that protrudes upwardly in the centerlinedirection. At the center of the central protruding part 71 a, the centerportion through hole 71 b, which is a through hole for holding theinternal pressure adjusting component 20, is formed. The leg portions 32a of the insertion portion 32 in the support body 30 of the internalpressure adjusting component 20 are inserted into the center portionthrough hole 71 b, and the plural outward protruding parts 32 b of theleg portions 32 a are spread out of the hole diameter of the centerportion through hole 71 b below thereof, and accordingly, the internalpressure adjusting component 20 is prevented from detaching from theholding member 70.

Moreover, in the bottom portion 71, plural through holes are formedaround the central protruding part 71 a. Hereinafter, the through holesformed around the central protruding part 71 a are referred to assurrounding through holes 71 c.

The side portion 72 is provided cylindrically to cover the ventilationmembrane 40 of the internal pressure adjusting component 20 or the outercircumferential portion of the cover 50. An upper end surface of theside portion 72 functions as a butted surface (a butted portion) of ajig that inserts the internal pressure adjusting component 20 when theinternal pressure adjusting component 20 is attached to the holdingmember 70. Therefore, the position of the upper end surface of the sideportion 72 in the centerline direction is same as the position of theupper end surface of the cover 50 of the internal pressure adjustingcomponent 20.

The attaching portion 73 includes a cylindrical part 73 a in a cylindershape and protruding parts 73 b that protrudes outwardly from an outercircumferential surface of the cylindrical part 73 a. The protrudingparts 73 b are formed at four locations at regular intervals in thecircumferential direction at the lower end portion of the cylindricalpart 73 a.

In a state where the protruding parts 73 b of the attaching portion 73are positioned to face cutouts 121 a formed in the housing 120, thecylindrical part 73 a is inserted into an insertion hole 121 formed inthe housing 120 and then rotated around the centerline at the positionwhere the protruding part 73 b enters the housing 120, and thereby theholding member 70 is fitted into the housing 120. Consequently, theventilation unit 1 is attached to the housing 120.

Note that the method of attaching the ventilation unit 1 to the housing120 is not particularly limited. For example, the holding member 70 maybe press-fitted into the housing 120. Moreover, for example, a malethread is formed, instead of providing the protruding parts 73 b, in thecylindrical part 73 a of the attaching portion 73, and the ventilationunit 1 may be attached to the housing 120 by screwing the male threadinto a female thread formed in the housing 120.

The material of the holding member 70 is harder than the material of theexplosion-proof valve 10. For example, a thermoplastic resin, which iseasily molded, or metal is preferred. As the thermoplastic resin,examples of thermoplastic resins except for elastomer can includepolybutylene terephthalate (PBT), polyethylene terephthalate (PET),polyphenylene sulfide (PPS), polysulfone (PS), polypropylene (PP),polyethylene (PE), ABS resin or a composite material thereof. Moreover,the examples of the material of the holding member 70 can include acomposite material made by combining a reinforcement, such as glassfiber or carbon fiber, or metal with the thermoplastic resin to improveheat resistance, humidity resistance, dimensional stability, rigidity orthe like.

The molding method of the holding member 70 is not particularly limited;examples thereof can include injection molding, compression molding,die-casting or cutting. Moreover, the support body 30 may be molded bycutting after die-casting.

(Sealing Member 80)

The sealing member 80 is an annular-shaped rubber member. The innerdiameter of the sealing member 80 is not less than the outer diameter ofthe cylindrical part 73 a of the attaching portion 73 in the holdingmember 70, and the outer diameter of the sealing member 80 is equal tothe outer diameter of the bottom portion 71 of the holding member 70.Then, when the holding member 70 is attached to the housing 120, thesealing member 80 is disposed between the holding member 70 and thehousing 120 to seal the holding member 70 and the housing 120. In otherwords, between the holding member 70 and the housing 120, the sealingmember 80 prevents liquids and solids from penetrating into the insideof the housing 120 from the outside of the housing 120 while blockingflow of gases between the inside of the housing 120 and the outside ofthe housing 120.

(Explosion-Proof Valve 10)

The explosion-proof valve 10 includes an annular portion 11 having anannular shape provided to the center, and an inclined portion 12extending from an outer circumferential part of the annular portion 11in a direction inclined with respect to the centerline direction anddownwardly. The inner diameter of the annular portion 11 is not morethan the outer diameter of the insertion portion 32 of the support body30, and the outer diameter of the annular portion 11 is larger than theouter diameter of the support portion 31 of the support body 30 or theouter diameter of the central protruding part 71 a of the holding member70. The annular portion 11 is press-fitted into the insertion portion 32of the support body 30, and thereby the explosion-proof valve 10 issupported by the support body 30.

The inclined portion 12 extends from the whole circumference of theouter circumferential part of the annular portion 11 obliquely downward,and when viewed in FIG. 5, the inclined portion 12 includes an uppersurface 12 a positioned at the upper side, a lower surface 12 bpositioned at the lower side, and a contact surface 12 c that intersectsthe centerline direction to be brought into contact with the bottomportion 71 of the holding member 70. The position where the contactsurface 12 c contacts a top surface of the bottom portion 71 of theholding member 70 is provided outside of the surrounding through holes71 c formed in the bottom portion 71. In other words, the radius fromthe centerline C in the contact surface 12 c is larger than a distancefrom the centerline C to an outermost part of the surrounding throughholes 71 c.

In the explosion-proof valve 10, the annular portion 11 is sandwichedbetween the support portion 31 of the support body 30 and the centralprotruding part 71 a of the bottom portion 71 in the holding member 70.Then, in the state where the annular portion 11 is sandwiched betweenthe support portion 31 of the support body 30 and the central protrudingpart 71 a of the holding member 70, the contact surface 12 c is broughtinto contact with the top surface of the bottom portion 71 in theholding member 70. The contact surface 12 c is brought into contact witha top surface of the bottom portion 71 of the holding member 70, andthereby a first flow path R1 (refer to FIG. 6), through which the gasescommunicate between the inside of the housing 120 and the outside of thehousing 120 via the surrounding through holes 71 c formed in the bottomportion 71 of the holding member 70, is closed.

The explosion-proof valve 10 is an elastic body, and examples of thematerial thereof can include a thermosetting elastomer or athermosetting rubber that is not softened by heating within a certainrange and has high heat resistance.

Then, the annular portion 11 is sandwiched between the support portion31 of the support body 30 and the central protruding part 71 a of thebottom portion 71 in the holding member 70, and thereby theexplosion-proof valve 10 seals between the support body 30 and theholding member 70. In other words, between the support body 30 and theholding member 70, the explosion-proof valve 10 prevents liquids andsolids from penetrating into the inside of the housing 120 from theoutside of the housing 120 while blocking flow of gases between theinside of the housing 120 and the outside of the housing 120.

FIG. 6 is a diagram showing a state in which the explosion-proof valve10 related to the first exemplary embodiment opened the first flow pathR1.

The explosion-proof valve 10 is elastically deformed when the internalpressure, which is the pressure inside the housing 120, is higher thanthe external pressure, which is the pressure outside the housing 120, bya value not less than a predetermined value, and the contact surface 12c is separated from the bottom portion 71 of the holding member 70, tothereby open the first flow path R1.

To put it another way, when the pressure difference between the internalpressure and the external pressure is less than a predetermined value,the explosion-proof valve 10 closes the first flow path R1 by bringingthe contact surface 12 c into contact with the bottom portion 71 of theholding member 70. Then, the shape (the width between the upper surface12 a and the lower surface 12 b) or material of the inclined portion 12is determined so that, when the internal pressure is higher than theexternal pressure by a value not less than a predetermined value,elastic deformation is caused and the contact surface 12 c is separatedfrom the bottom portion 71 of the holding member 70, to thereby open thefirst flow path R1.

Note that, when the external pressure is higher than the internalpressure, the contact surface 12 c is kept in contact with the bottomportion 71 of the holding member 70, and accordingly, theexplosion-proof valve 10 continues to close the first flow path R1.Consequently, the explosion-proof valve 10 prevents liquids and solidsfrom penetrating into the inside of the housing 120 from the outside ofthe housing 120, while blocking flow of gases between the inside of thehousing 120 and the outside of the housing 120, via the first flow pathR1.

(Action)

In the ventilation unit 1 configured as described above, when a pressuredifference is generated between the pressure inside the housing 120(internal pressure) and the pressure outside the housing 120 (externalpressure), the pressure difference is eliminated by causing gases tocommunicate between the inside of the housing 120 and the outside of thehousing 120 via the ventilation membrane 40. In other words, the flowpaths configured with the communicating hole 33 formed in the supportportion 31 of the support body 30 or the gaps between the extendingportions 52 function as a second flow path R2 of gases communicatingbetween the inside of the housing 120 and the outside of the housing120. When the pressure difference is generated between the internalpressure and the external pressure, the pressure difference iseliminated by causing the gases to communicate through the second flowpath R2 via the ventilation membrane 40.

If the pressure inside the housing 120 (the internal pressure) israpidly increased, such as when abnormality occurs in the battery 110,the contact surface 12 c of the explosion-proof valve 10 is separatedfrom the bottom portion 71 of the holding member 70, and theexplosion-proof valve 10 is elastically deformed to open the first flowpath R1. Consequently, gases flow from the inside of the housing 120 tothe outside of the housing 120 via the first flow path R1, and therebythe pressure difference between the pressure inside the housing 120 (theinternal pressure) and the pressure outside the housing 120 (theexternal pressure) is eliminated.

(Assembly)

The ventilation unit 1 configured as described above is assembled asfollows.

First, the ventilation membrane 40 is supported (for example, bywelding) by the support body 30 of the internal pressure adjustingcomponent 20, and the inward protruding parts 52 a of the cover 50 arefitted into the concave parts 31 c formed in the support body 30, andthereby the internal pressure adjusting component 20 is assembled. Afterthe internal pressure adjusting component 20 is assembled, the annularportion 11 of the explosion-proof valve 10 is press-fitted into theinsertion portion 32 of the support body 30 in the internal pressureadjusting component 20, to thereby integrate the internal pressureadjusting component 20 and the explosion-proof valve 10. Other thanthis, examples of the integrating method can include joining by weldingthe explosion-proof valve 10 to the support body 30 of the internalpressure adjusting component 20. Moreover, the explosion-proof valve 10and the support body 30 of the internal pressure adjusting component 20may be bonded by a bonding agent or a double-faced tape. In addition,the explosion-proof valve 10 and the support body 30 of the internalpressure adjusting component 20 may be integrated by insert molding.Then, the internal pressure adjusting component 20 supporting theexplosion-proof valve 10 is inserted into the center portion throughhole 71 b formed in the bottom portion 71 of the holding member 70.

FIG. 7A is a diagram showing a state before the internal pressureadjusting component 20 is inserted into the holding member 70. FIG. 7Bis a diagram showing a state after the internal pressure adjustingcomponent 20 is inserted into the holding member 70.

When the internal pressure adjusting component 20 is inserted into thecenter portion through hole 71 b formed in the holding member 70, by asurface larger than the outer diameter of the side portion 72 of theholding member 70, for example, a jig 250 with a lower end surface 251,which is a circle having a diameter larger than the outer diameter ofthe side portion 72 of the holding member 70, the top portion 51 of thecover 50 in the internal pressure adjusting component 20 is pressurized.Then, as shown in FIG. 7B, the internal pressure adjusting component 20is pressed into the holding member 70 until the lower end surface 251 ofthe jig 250 is butted against the side portion 72 of the holding member70. Consequently, the outward protruding parts 32 b of the leg portions32 a in the insertion portion 32 of the support body 30 are positionedbelow the center portion through hole 71 b formed in the bottom portion71 of the holding member 70. Then, the outward protruding parts 32 b ofthe support body 30 are butted against the bottom portion 71 of theholding member 70, and thereby the internal pressure adjusting component20 is prevented from detaching from the holding member 70.

(Inspection)

In the ventilation unit 1 related to the first exemplary embodiment,after the ventilation unit 1 is assembled, it is possible to easilyinspect whether or not the explosion-proof valve 10 functions. In otherwords, it is possible to inspect the explosion-proof valve 10 that, whenthe pressure on the lower surface 12 b side of the inclined portion 12of the explosion-proof valve 10 is increased to be higher than thepressure on the upper surface 12 a side of the inclined portion 12 by avalue not less than a predetermined value, the contact surface 12 c ofthe explosion-proof valve 10 is separated from the bottom portion 71 ofthe holding member 70 to open the first flow path R1.

For example, if the explosion-proof valve performs the opening operationwith breaking or detaching of a part of components, the inspection ofwhether or not the explosion-proof valve functions accompanies actualbreaking or detaching; therefore, the inspection cannot be performedeasily. For example, it is difficult to deal with those broken by theinspection as products.

In contrast thereto, in the ventilation unit 1 related to the exemplaryembodiment, the explosion-proof valve 10 is elastically deformed toseparate the contact surface 12 c from the bottom portion 71 of theholding member 70, and thereby the first flow path R1 is opened.Therefore, since the contact surface 12 c contacts the bottom portion 71of the holding member 70 to close the first flow path R1 after theinspection is completed, the ventilation unit 1 can be used as a productafter inspection.

FIG. 8 is a diagram showing an example of a state after the function ofthe explosion-proof valve 10 related to the first exemplary embodimentwas inspected. In the state shown in FIG. 8, the inclined portion 12 isdeformed so that the upper surface 12 a and the lower surface 12 b arereversed with respect to the annular portion 11 as a fulcrum (the uppersurface 12 a is positioned inside (the centerline C side) and the lowersurface 12 b is positioned outside).

Even though the deformation in the state shown in FIG. 8 is achieved byincreasing the pressure on the lower surface 12 b side of the inclinedportion 12 of the explosion-proof valve 10 to be higher than thepressure on the upper surface 12 a side of the inclined portion 12 by avalue not less than a predetermined value, the contact surface 12 c canbe returned again to contact the bottom portion 71 of the holding member70, to thereby close the first flow path R1, because the material of theexplosion-proof valve 10 is the thermosetting elastomer or thethermosetting rubber. Also, from this, according to the ventilation unit1 related to the first exemplary embodiment, it is possible to easilyinspect whether or not the explosion-proof valve 10 functions after theventilation unit 1 has been assembled, as compared to the case where,for example, the explosion-proof valve performs the opening operationwith breaking or detaching of a part of components.

Note that, in the above-described first exemplary embodiment, the modein which the internal pressure adjusting component 20 and theexplosion-proof valve 10 are integrated is taken as an example; however,the present invention is not particularly limited to such a mode. Forexample, the internal pressure adjusting component 20 and theexplosion-proof valve 10 may be separately assembled to the holdingmember 70 in a state not to be integrated. Even in such a case, it isdesirable that, when the internal pressure adjusting component 20 isattached to the holding member 70, the annular portion 11 of theexplosion-proof valve 10 is sandwiched between the internal pressureadjusting component 20 and the holding member 70 in the state of beingcompressed therebetween to seal between the internal pressure adjustingcomponent 20 and the holding member 70.

Second Exemplary Embodiment

FIG. 9 is a cross-sectional view of a ventilation unit 2 related to asecond exemplary embodiment.

The ventilation unit 2 related to the second exemplary embodiment isdifferent from the ventilation unit 1 related to the first exemplaryembodiment in the explosion-proof valve 10 and the holding member 70.Hereinafter, with respect to the ventilation unit 2 related to thesecond exemplary embodiment, points different from those of theventilation unit 1 related to the first exemplary embodiment will bedescribed, but points same as those of the ventilation unit 1 related tothe first exemplary embodiment will be assigned with the same signs anddetailed description thereof will be omitted.

The ventilation unit 2 related to the second exemplary embodimentincludes an explosion-proof valve 210 and a holding member 270.

(Holding Member 270)

The holding member 270 includes a disk-shaped bottom portion 271, theside portion 72 and the attaching portion 73.

The bottom portion 271 related to the second exemplary embodiment isdifferent from the bottom portion 71 related to the first exemplaryembodiment in the point that the bottom portion 271 is not provided withthe central protruding part 71 a upwardly protruding at the centerportion. Then, in the bottom portion 271 related to the second exemplaryembodiment, a center portion through hole 271 b, which is a through holefor holding the internal pressure adjusting component 20, is formed. Theleg portions 32 a of the insertion portion 32 in the support body 30 ofthe internal pressure adjusting component 20 are inserted into thecenter portion through hole 271 b, and the plural outward protrudingparts 32 b of the leg portions 32 a are spread out of the hole diameterof the center portion through hole 271 b below thereof, and accordingly,the internal pressure adjusting component 20 is prevented from detachingfrom the holding member 270.

Moreover, in the bottom portion 271, plural through holes are formedaround the center portion through hole 271 b. Hereinafter, the throughholes formed around the center portion through hole 271 b are referredto as surrounding through holes 271 c.

(Explosion-Proof Valve 210)

The explosion-proof valve 210 related to the second exemplary embodimentincludes an annular portion 211 having an annular shape provided to thecenter, and an inclined portion 212 extending from an outercircumferential part of the annular portion 211 in a direction inclinedwith respect to the centerline direction and upwardly.

The inner diameter of the annular portion 211 is not more than the outerdiameter of the insertion portion 32 of the support body 30, and theouter diameter of the annular portion 211 is set to be positioned insidethe surrounding through holes 271 c formed in the holding member 270.

The inclined portion 212 extends from the whole circumference of theouter circumferential part of the annular portion 211 obliquely upward,and when viewed in FIG. 9, the inclined portion 212 includes an uppersurface 212 a positioned at the upper side, a lower surface 212 bpositioned at the lower side, and an intersecting surface 212 c thatintersects the centerline direction.

In the explosion-proof valve 210, the annular portion 211 is sandwichedbetween the support portion 31 of the support body 30 and the bottomportion 271 of the holding member 270. In the state where the annularportion 211 is sandwiched between the support portion 31 of the supportbody 30 and the holding member 270, an intersecting line 212 d of thelower surface 212 b and the intersecting surface 212 c contacts theinner circumferential surface of the side portion 72 of the holdingmember 270, and thereby the first flow path R1, through which the gasescommunicate between the inside of the housing 120 and the outside of thehousing 120 via the surrounding through holes 271 c formed in the bottomportion 271 of the holding member 270, is closed.

FIG. 10 is a diagram showing a state in which the explosion-proof valve210 related to the second exemplary embodiment opened the first flowpath R1.

The explosion-proof valve 210 is elastically deformed when the internalpressure, which is the pressure inside the housing 120, is higher thanthe external pressure, which is the pressure outside the housing 120, bya value not less than a predetermined value, and the intersecting line212 d is separated from the side portion 72 of the holding member 270,to thereby open the first flow path R1.

To put it another way, when the pressure difference between the internalpressure and the external pressure is less than a predetermined value,the explosion-proof valve 210 closes the first flow path R1 by bringingthe intersecting line 212 d into contact with the side portion 72 of theholding member 270. Then, the shape (the width between the upper surface212 a and the lower surface 212 b) or material of the inclined portion212 is determined so that, when the internal pressure is higher than theexternal pressure by a value not less than a predetermined value,elastic deformation is caused and the intersecting line 212 d isseparated from the side portion 72 of the holding member 270, to therebyopen the first flow path R1.

Note that, when the external pressure is higher than the internalpressure, the intersecting line 212 d is kept in contact with the sideportion 72 of the holding member 270, and accordingly, theexplosion-proof valve 210 continues to close the first flow path R1.Consequently, the explosion-proof valve 210 prevents liquids and solidsfrom penetrating into the inside of the housing 120 from the outside ofthe housing 120, while blocking flow of gases between the inside of thehousing 120 and the outside of the housing 120, via the first flow pathR1.

(Action)

In the ventilation unit 2 related to the second exemplary embodimentconfigured as described above, when a pressure difference is generatedbetween the pressure inside the housing 120 (internal pressure) and thepressure outside the housing 120 (external pressure), the pressuredifference is eliminated by causing gases to communicate between theinside of the housing 120 and the outside of the housing 120 via theventilation membrane 40.

If the pressure inside the housing 120 (the internal pressure) israpidly increased, such as when abnormality occurs in the battery 110,the intersecting line 212 d of the explosion-proof valve 210 isseparated from the side portion 72 of the holding member 270, and theexplosion-proof valve 210 is elastically deformed to open the first flowpath R1. Consequently, gases flow from the inside of the housing 120 tothe outside of the housing 120 via the first flow path R1, and therebythe pressure difference between the pressure inside the housing 120 (theinternal pressure) and the pressure outside the housing 120 (theexternal pressure) is eliminated.

(Assembly)

The ventilation unit 2 related to the second exemplary embodimentconfigured as described above is assembled as follows.

First, the internal pressure adjusting component 20 is assembled asdescribed above, and thereafter, the annular portion 211 of theexplosion-proof valve 210 is press-fitted into the insertion portion 32of the support body 30 in the internal pressure adjusting component 20.Then, the internal pressure adjusting component 20 supporting theexplosion-proof valve 210 is inserted into the center portion throughhole 271 b formed in the bottom portion 271 of the holding member 270.

When the internal pressure adjusting component 20 is inserted into thecenter portion through hole 271 b formed in the holding member 270, thetop portion 51 of the cover 50 in the internal pressure adjustingcomponent 20 is pressurized by the jig 250. Then, the internal pressureadjusting component 20 is pressed into the holding member 270 until thelower end surface 251 of the jig 250 is butted against the side portion72 of the holding member 270. Consequently, the outward protruding parts32 b of the leg portions 32 a in the insertion portion 32 of the supportbody 30 are positioned below the center portion through hole 271 bformed in the bottom portion 271 of the holding member 270. Then, theoutward protruding parts 32 b of the support body 30 are butted againstthe bottom portion 271 of the holding member 270, and thereby theinternal pressure adjusting component 20 is prevented from detachingfrom the holding member 270.

(Inspection)

In the ventilation unit 2 related to the second exemplary embodiment,after the ventilation unit 2 is assembled, it is possible to easilyinspect whether or not the explosion-proof valve 210 functions. In otherwords, it is possible to inspect the explosion-proof valve 210 that,when the pressure on the lower surface 212 b side of the inclinedportion 212 of the explosion-proof valve 210 is increased to be higherthan the pressure on the upper surface 212 a side of the inclinedportion 212 by a value not less than a predetermined value, theintersecting line 212 d of the explosion-proof valve 210 is separatedfrom the side portion 72 of the holding member 270 to open the firstflow path R1. Then, in the ventilation unit 2 related to the secondexemplary embodiment, since the intersecting line 212 d contacts theside portion 72 of the holding member 270 to close the first flow pathR1 after the inspection is completed, the ventilation unit 2 can be usedas a product after inspection. Therefore, according to the ventilationunit 2 related to the second exemplary embodiment, it is possible toeasily inspect whether or not the explosion-proof valve 210 functionsafter the ventilation unit 2 has been assembled, as compared to the casewhere, for example, the explosion-proof valve performs the openingoperation with breaking or detaching of a part of components.

Note that the shape of the inclined portion 212 of the explosion-proofvalve 10 is not particularly limited as long as capable of contactingthe side portion 72 of the holding member 720. For example, the inclinedportion 212 may include the upper surface 212 a positioned at the upperside, the lower surface 212 b positioned at the lower side, and asurface to be brought into surface contact with the innercircumferential surface of the side portion 72 when the inclined portion212 contacts the side portion 72 of the holding member 270, forinstance, a surface in parallel with the centerline direction.

Third Exemplary Embodiment

FIG. 11 is a perspective view of components constituting the ventilationunit 3 related to the third exemplary embodiment. FIG. 12 is across-sectional view of the ventilation unit 3 related to the thirdexemplary embodiment.

Hereinafter, with respect to the ventilation unit 3 related to the thirdexemplary embodiment, points different from those of the ventilationunit 1 related to the first exemplary embodiment will be described, butpoints same as those of the ventilation unit 1 related to the firstexemplary embodiment will be assigned with the same signs and detaileddescription thereof will be omitted.

The ventilation unit 3 related to the third exemplary embodimentincludes an explosion-proof valve 310 that permits gases to flow fromthe inside of the housing 120 to the outside of the housing 120 wheninternal pressure, which is the pressure inside the housing 120 ishigher than pressure outside the housing 120 (external pressure) by avalue not less than a predetermined value, and blocks the flow of thegases from the inside of the housing 120 to the outside of the housing120 when the internal pressure is not higher than the external pressureby a value not less than the predetermined value.

Moreover, the ventilation unit 3 includes the ventilation membrane 40that prevents liquids and solids from penetrating into the inside of thehousing 120 from the outside of the housing 120 while permitting flow ofgases between the inside of the housing 120 and the outside of thehousing 120.

Moreover, the ventilation unit 3 includes a support body 330 thatsupports the ventilation membrane 40 and the explosion-proof valve 310,while having a communicating hole 340 formed therein to communicate theinside of the housing 120 and the outside of the housing 120 and beinginserted into the insertion hole 121 formed in the housing 120.

(Support Body 330)

The support body 330 is a cylinder-shaped member, and the outer diameterthereof is not more than the hole diameter of the insertion hole 121formed in the housing 120. The support body 330 includes an inwardprotruding portion 331 that protrudes inwardly from the innercircumferential surface over the whole circumference. Moreover, thesupport body 330 includes: an upper end outward protruding portion 332that protrudes outwardly from the outer circumferential surface at theupper end portion; a lower end outward protruding portion 333 thatprotrudes outwardly from the outer circumferential surface at the lowerend portion; and a middle-stage outward protruding portion 334 thatprotrudes outwardly from the outer circumferential surface between theupper end outward protruding portion 332 and the lower end outwardprotruding portion 333.

The ventilation membrane 40 is supported by inward protruding portion331 of the support body 330 to cover the communicating hole 340.Examples of the supporting method can include joining by welding theventilation membrane 40 to the inward protruding portion 331. Other thanthis, ventilation membrane 40 and the inward protruding portion 331 maybe bonded by a bonding agent or a double-faced tape. Moreover, theventilation membrane 40 and the support body 330 may be integrated byinsert molding. Alternatively, the ventilation membrane 40 may be swagedto the support body 330.

When the ventilation unit 3 is attached to the housing 120, the lowerend outward protruding portion 333 is positioned beneath the insertionhole 121 formed in the housing 120, and the lower end outward protrudingportion 333 is butted against the housing 120, to thereby prevent theventilation unit 3 from detaching from the housing 120.

The middle-stage outward protruding portion 334 is fitted into a concavepart 313 a, which will be described later, of the explosion-proof valve310 to support the explosion-proof valve 310.

(Explosion-Proof Valve 310)

The explosion-proof valve 310 includes an annular portion 311 having anannular shape provided to the center, an inclined portion 312 extendingfrom an outer circumferential part of the annular portion 311 in adirection inclined with respect to the centerline direction anddownwardly, and a downward protruding portion 313 protruding downwardfrom an inside end portion in the annular portion 311.

In the downward protruding portion 313, the concave part 313 a having acylindrical shape and concaved outwardly from the inner circumferentialsurface is formed.

The inner diameter of the annular portion 311 and the downwardprotruding portion 313 is not more than the outer diameter of thesupport body 330, and the explosion-proof valve 310 is press-fitted overthe outer circumferential surface of the support body 330, and therebysupported by the support body 330. Then, the middle-stage outwardprotruding portion 334 of the support body 330 is fitted into theconcave part 313 a of the downward protruding portion 313, and therebythe position of the explosion-proof valve 310 in the centerlinedirection is determined.

The inclined portion 312 extends from the whole circumference of theouter circumferential part of the annular portion 311 obliquelydownward, and when viewed in FIG. 12, the inclined portion 312 includesan upper surface 312 a positioned at the upper side, a lower surface 312b positioned at the lower side, and a contact surface 312 c thatintersects the centerline direction to be brought into contact with anouter surface of the housing 120. The position where the contact surface312 c contacts the outer surface of the housing 120 is provided outsideof the surrounding through holes 121 c formed around the insertion hole121 of the housing 120. In other words, when the ventilation unit 3 isattached to the housing 120, the radius from the centerline C in thecontact surface 312 c is larger than a distance from the centerline C toan outermost part of the surrounding through holes 121 c.

In the explosion-proof valve 310, the annular portion 311 and thedownward protruding portion 313 are sandwiched between the upper endoutward protruding portion 332 of the support body 330 and the housing120. Then, in the state where the annular portion 311 and the downwardprotruding portion 313 are sandwiched between the upper end outwardprotruding portion 332 of the support body 330 and the housing 120, thecontact surface 312 c is brought into contact with the outer surface ofthe housing 120. The contact surface 312 c is brought into contact withthe outer surface of the housing 120, and thereby the first flow pathR1, through which the gases communicate between the inside of thehousing 120 and the outside of the housing 120 via the surroundingthrough holes 121 c formed in the housing 120, is closed.

The explosion-proof valve 310 is an elastic body, and examples of thematerial thereof can include a thermosetting elastomer or athermosetting rubber that is not softened by heating within a certainrange and has high heat resistance.

Then, the annular portion 311 and the downward protruding portion 313are sandwiched between the upper end outward protruding portion 332 ofthe support body 330 and the housing 120, and thereby theexplosion-proof valve 310 seals between the support body 330 and thehousing 120.

In other words, between the outer surface of the support body 330 andthe housing 120, the explosion-proof valve 310 prevents liquids andsolids from penetrating into the inside of the housing 120 from theoutside of the housing 120 while blocking flow of gases between theinside of the housing 120 and the outside of the housing 120.

FIG. 13 is a diagram showing a state in which the explosion-proof valve310 related to the third exemplary embodiment opened the first flow pathR1.

The explosion-proof valve 310 is elastically deformed when the internalpressure, which is the pressure inside the housing 120, is higher thanthe external pressure, which is the pressure outside the housing 120, bya value not less than a predetermined value, and the contact surface 312c is separated from the outer surface of the housing 120, to therebyopen the first flow path R1.

To put it another way, when the pressure difference between the internalpressure and the external pressure is less than a predetermined value,the explosion-proof valve 310 closes the first flow path R1 by bringingthe contact surface 312 c into contact with the outer surface of thehousing 120. Then, the shape (the width between the upper surface 312 aand the lower surface 312 b) or material of the inclined portion 312 isdetermined so that, when the internal pressure is higher than theexternal pressure by a value not less than a predetermined value,elastic deformation is caused and the contact surface 312 c is separatedfrom the outer surface of the housing 120, to thereby open the firstflow path R1.

Note that, when the external pressure is higher than the internalpressure, the contact surface 312 c is kept in contact with the outersurface of the housing 120, and accordingly, the explosion-proof valve310 continues to close the first flow path R1. Consequently, theexplosion-proof valve 310 prevents liquids and solids from penetratinginto the inside of the housing 120 from the outside of the housing 120,while blocking flow of gases between the inside of the housing 120 andthe outside of the housing 120, via the first flow path R1.

(Action)

In the ventilation unit 3 configured as described above, when a pressuredifference is generated between the pressure inside the housing 120(internal pressure) and the pressure outside the housing 120 (externalpressure), the pressure difference is eliminated by causing gases tocommunicate between the inside of the housing 120 and the outside of thehousing 120 via the ventilation membrane 40. In other words, the flowpaths configured with the communicating hole 340 formed in the supportbody 330 and so forth function as a second flow path R2 of gasescommunicating between the inside of the housing 120 and the outside ofthe housing 120. When the pressure difference is generated between theinternal pressure and the external pressure, the pressure difference iseliminated by causing the gases to communicate through the second flowpath R2 via the ventilation membrane 40.

If the pressure inside the housing 120 (the internal pressure) israpidly increased, such as when abnormality occurs in the battery 110,the contact surface 312 c of the explosion-proof valve 310 is separatedfrom the outer surface of the housing 120, and the explosion-proof valve310 is elastically deformed to open the first flow path R1.Consequently, gases flow from the inside of the housing 120 to theoutside of the housing 120 via the first flow path R1, and thereby thepressure difference between the pressure inside the housing 120 (theinternal pressure) and the pressure outside the housing 120 (theexternal pressure) is eliminated.

(Assembly)

In the ventilation unit 3 configured as described above, theexplosion-proof valve 310 is press-fitted over the outer circumferentialsurface of the support body 330, and thereby the support body 330 andthe explosion-proof valve 310 are integrated. The middle-stage outwardprotruding portion 334 of the support body 330 is fitted into theconcave part 313 a formed in the downward protruding portion 313 of theexplosion-proof valve 310, and thereby the position of theexplosion-proof valve 310 in the centerline direction is determined.

(Inspection)

In the ventilation unit 3 related to the third exemplary embodiment,after the ventilation unit 3 is assembled, it is possible to easilyinspect whether or not the explosion-proof valve 310 functions. Theventilation unit 3 is attached to a plate-like inspection jig in which athrough hole, like the insertion hole 121 and the surrounding throughholes 121 c of the housing 120, is formed. Then, it is possible toinspect the explosion-proof valve 310 that, when the pressure on thelower surface 312 b side of the inclined portion 312 of theexplosion-proof valve 310 is increased to be higher than the pressure onthe upper surface 312 a side of the inclined portion 312 by value notless than a predetermined value, the contact surface 312 c of theexplosion-proof valve 310 is separated from the surface of theinspection jig to open the first flow path R1. Then, in the ventilationunit 3 related to the third exemplary embodiment, since the contactsurface 312 c of the explosion-proof valve 310 contacts the surface ofthe inspection jig to close the first flow path R1 after the inspectionis completed, the ventilation unit 3 can be used as a product afterinspection. Therefore, according to the ventilation unit 3 related tothe third exemplary embodiment, it is possible to easily inspect whetheror not the explosion-proof valve 310 functions after the ventilationunit 3 has been assembled, as compared to the case where, for example,the explosion-proof valve performs the opening operation with breakingor detaching of a part of components.

FIG. 14 is a diagram showing an example of a state after the function ofthe explosion-proof valve 310 related to the third exemplary embodimentwas inspected. In the state shown in FIG. 14, the inclined portion 312is deformed so that the upper surface 312 a and the lower surface 312 bare reversed with respect to the annular portion 311 as a fulcrum (theupper surface 312 a is positioned inside (the centerline C side) and thelower surface 312 b is positioned outside).

Even though the deformation in the state shown in FIG. 14 is achieved byincreasing the pressure on the lower surface 312 b side of the inclinedportion 312 of the explosion-proof valve 310 to be higher than thepressure on the upper surface 312 a side of the inclined portion 312 bya value not less than a predetermined value, the contact surface 312 ccan be returned again to contact the surface of the inspection jig, tothereby close the first flow path R1, because the material of theexplosion-proof valve 310 is the thermosetting elastomer or thethermosetting rubber. Also, from this, according to the ventilation unit3 related to the third exemplary embodiment, it is possible to easilyinspect whether or not the explosion-proof valve 310 functions after theventilation unit 3 has been assembled, as compared to the case where,for example, the explosion-proof valve performs the opening operationwith breaking or detaching of a part of components.

REFERENCE SIGNS LIST

-   1, 2, 3 Ventilation unit-   10, 210, 310 Explosion-proof valve-   20 Internal pressure adjusting component-   30, 330 Support body-   40 Ventilation membrane-   70, 270 Holding member-   80 Sealing member-   100 Battery pack

1-10. (canceled)
 11. A ventilation unit comprising: a first ventilationbody that permits gas to flow from an inside of a housing to an outsideof the housing when internal pressure, which is pressure inside thehousing, is higher than external pressure, which is pressure outside thehousing, by a value not less than a predetermined value, and is capableof returning to block flow of the gas from the inside of the housing tothe outside of the housing; and a second ventilation body that permitsgas to flow between the inside of the housing and the outside of thehousing even when a pressure difference between the internal pressureand the external pressure is less than the predetermined value.
 12. Theventilation unit according to claim 11, further comprising: a supportmember that supports the first ventilation body and the secondventilation body.
 13. The ventilation unit according to claim 12,further comprising: a holding member that holds the support member, andis attached to the housing.
 14. The ventilation unit according to claim11, wherein the second ventilation body prevents a liquid and a solidfrom penetrating into the inside of the housing from the outside of thehousing.
 15. The ventilation unit according to claim 12, wherein thesecond ventilation body prevents a liquid and a solid from penetratinginto the inside of the housing from the outside of the housing.
 16. Theventilation unit according to claim 13, wherein the second ventilationbody prevents a liquid and a solid from penetrating into the inside ofthe housing from the outside of the housing.
 17. A ventilation unitcomprising: a first ventilation body that closes a first flow path whena pressure difference between internal pressure, which is pressureinside a housing, and external pressure, which is pressure outside thehousing, is a value less than a predetermined value, and is elasticallydeformed to open the first flow path when the internal pressure ishigher than the external pressure by a value not less than thepredetermined value; and a second ventilation body that is provided to asecond flow path and permits gas to flow between the inside of thehousing and the outside of the housing via the second flow path evenwhen the pressure difference between the internal pressure and theexternal pressure is less than the predetermined value.
 18. Theventilation unit according to claim 17, further comprising: a supportmember that supports the first ventilation body and the secondventilation body.
 19. The ventilation unit according to claim 18,further comprising: a holding member that holds the support member, andis attached to the housing.
 20. The ventilation unit according to claim19, wherein the support member is attached to the holding member bybeing inserted into the holding member, the second ventilation body isfastened to the support member, and the first ventilation body issandwiched between the support member and the holding member.
 21. Theventilation unit according to claim 20, wherein the holding membercomprises a butted portion, against which a jig used in inserting thesupport member into the holding member is butted, and a position of thesupport member with respect to the holding member is determined byinserting the support member into the holding member until the jig isbutted against the butted portion.
 22. The ventilation unit according toclaim 19, wherein the first ventilation body closes the first flow pathby contacting the holding member, and opens the first flow path byseparating from the holding member.